In this paper, we present a new experimental procedure which aims at measuring adsorption isotherms and heats of adsorption of volatile organic compounds (VOCs) on porous media in the low relative pressure range for temperatures ranging from 303 to 573 K. The experimental set-up and the experimental dynamic procedure are presented as well as a complete report on the treatment of the rough experimental results to obtain the adsorption isotherms and the adsorption heat curves. Measurement accuracy and repeatability are given. The maximum measurement error is 3% on the adsorbed mass, 9% on the partial pressure of VOC and 15% on the adsorption heat. Results are provided for a toluene/NaY system (isotherm and adsorption heat curve at 423 K in the pressure range 0.4-2000 Pa).

Both the inverse gas chromatographic method and the dynamic gravimetric-calorimetric method were tested in order to determine the Henry constant for toluene on a Na-faujasite type zeolite. We used the pulse technique for the chromatographic method and a system generating low concentration of VOC in a helium flow for the gravimetric technique. The experimental determinations of the Henry constants for toluene were achieved in two different temperature ranges (from 363 to 548 K for gravimetry and from 548 to 673 K for chromatography). The results presented in this paper show the complementarity of two different techniques for the Henry constants determination. The Henry constants obtained with the two techniques at 548 K differ from 8%.

In this paper, we propose a comparative study between a gravimetric apparatus operating under dynamic conditions and a pulse chromatographic device developed for the determination of Henry constants of adsorption for VOC–zeolite systems. In both cases, we provide a description of the experimental set-up and procedure, as well as a complete report on the treatment of the rough experimental data. The experimental errors are also discussed. The comparison work is based on the study of the adsorption of toluene on a NaY zeolite (Si/Al 2.43) for temperatures ranging from 503 to 623 K. The maximal discrepancy found between the experimental Henry constants was 15.0%. The pulse chromatographic method is only dedicated to high-temperature measurements. For low-temperature experiments, the rough data cannot be treated in an efficient way, and it is not possible to obtain reliable Henry constant values. The dynamic gravimetric method is not temperature limited. It is however time-consuming, especially when low-temperature measurements (not presented in this paper) are concerned. Both methods are complementary if the determination of Henry constants is required in a wide temperature range.

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In this paper, we present a new experimental technique and a mathematical procedure for the calculation of the isosteric heats of adsorption of VOC-zeolite systems. This procedure provides a continuous isosteric heat curve over a large coverage ratio range including the low-coverage area. Results are given for a toluene-NaY system at 423 K. The validity of the method is discussed by comparison with other methods.